Known in the art, there is the U.S. Pat. No. 4,519,039 of Bhupendra S. SURANA et al, granted on May 21, 1985 in which there is described a programmable controller including coil diameter calculator, strip speed derivation and inertia compensation. The controller is associated with a reel system for the generation in normalized digital form of a coil diameter of the reel instantaneously to allow initial calibration between successive coil winding and unwinding operations and automatic generation of a current reference for reel motor drive control.
Also known in the art, there is the U.S. Pat. No. 4,631,682 of David T. NG et al, granted on Dec. 23, 1986, in which there is described a control system which provides automatic control of winder deceleration and stopping to a preset sheet length, or preset roll diameter. The system utilizes a closed loop control of drive deceleration and automatic compensation for layers slabbed off following a sheetbreak.
Also known in the art, there is the U.S. Pat. No. 5,086,984 Of Douglas E. TUREK et al, granted on Feb. 11, 1992, in which there is described a method of predicting final yarn package diameter during winding of yarn onto the package. The yarn is to be wound onto the package for a known period of time to obtain the final yarn package diameter. The method comprises the steps of: measuring the time for the package to grow to a known diameter, and predicting yarn package diameter using a predetermined correlation.
Also known in the art, there are the U.S. Pat. No. 4,913,366; 4,883,233; 4,811,915; 3,910,516; and 3,792,820 which describe different apparatuses and methods relating to the production of a roll of material.
In the paper industry, big primary roll are used to produce smaller secondary rolls which will be sold to clients. When successive primary rolls are used to produce secondary rolls, the amount of paper wound around each primary roll with identical diameter will not produce the same amount of material on secondary rolls because the compression rate of the paper wound around each primary roll with respect to material wound around their respective secondary rolls varies from time to time because the operating conditions of the machines used to produce secondary rolls from a primary roll are not exactly the same from time to time.
Accordingly, to solve this problem, it is known to wound around each primary roll an additional amount of paper to be sure that there will be enough paper for the secondary rolls that should be produced.
One problem with this is that a certain amount of paper is lost at the end of each primary roll when it is unrolled.
None of the above patents provides a method or an apparatus that takes into account the fact that the compression rate at which the paper is wound around a primary roll with respect to secondary rolls is not constant.
It is an object of the present invention to provide a method and an apparatus for estimating with more precision the final diameter of the primary roll so that the loss of material when said primary roll is used to produce secondary rolls is reduced to minimum.